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The present paper discusses the geochemical affinities, origin and ages of Jurassic granitoids of the Sanandaj-Sirjan Zone (SaSZ) in the eastern part of the Zagros Thrust Zone. A multidisciplinary, integrated approach was carried out using existing granitoid geochemical data (major, trace, rare earth element and isotopes) and knowledge of the regional geology (geodynamic and metamorphic setting), coupled with geophysical data (magnetic susceptibility) from granitoids in the SaSZ. We re-interpret and re-classify the Jurassic granitoids of this zone into three main genetic groups: S-type, I-type and A-type subduction-related ones. In the central to southern part of the Sanandaj-Sirjan zone (between Hamadan and Sirjan), S-type magmatism appeared between 178 and 160 Ma during the Cimmerian orogeny, due to continental collision. To the north of the Sanandaj-Sirjan zone (between Sanandaj and Ghorveh), I-type and A-type magmatism occurred between 158 and 145 Ma. This heterogenic tectonomagmatic system along the SaSZ suggests a heterogenic subcontinental lithospheric mantle, resulting in two Jurassic tectonomagmatic zones of (1) the Sanandaj-Ghorveh Zone and (2) the Hamadan-Sirjan Zone.

The Cheshmeh Khuri prospecting area, part of the Tertiary volcanic-plutonic rocks in the Lut Block (central eastern Iran), comprises Middle Eocene granitoid and volcanic (with basaltic andesite to rhyolite composition) sequences that intruded pyroclastic rocks. Copper mineralization is related to the granitoid rocks. The mafic rocks occur mainly as dykes and are related to a younger magmatic activity (post-mineralization) in the area. The main hydrothermal alteration zones include quartz-sericite-pyrite ± carbonate (QSP ± C), argillic, and propylitic. Mineralization (pyrite, chalcocite, chalcopyrite, sphalerite, galena and magnetite) occurs as disseminated, stockwork and vein-type. The granitoids have features typical of high-K calk-alkaline, metaluminous, and belong to magnetite granitoid series. Primitive mantle normalized trace element spider diagrams display enrichment in LILE, such as Rb, Ba, and Cs, compared to those of HFSE. Chondrite-normalized REE plots show moderately to slightly strong LREE enriched patterns, and a negligible negative Eu anomaly. Rb-Sr whole rock–feldspar–biotite-hornblende and zircon U-Pb ages between ~44.6 and ~43.4 Ma (Middle Eocene) were obtained in granitoid samples. Initial 87Sr/86Sr ratios of granitoids range from 0.7047 to 0.7054, and their eNdi values vary from −1.1 to +0.8. Initial 87Sr/86Sr ratios of mafic rocks range from 0.7043 to 0.7047, and the eNdi values vary from +0.7 to +3.5. The whole set of geochemical data of rocks in the study area indicate an origin of the parental melts in a subduction-modified upper mantle in post-collisional extension-related zone. The primitive magmas of granitoids underwent contamination and assimilation through being exposed to the continental crust, while primitive magmas of the mafic rocks do not have relevant crustal contribution. The geochemical and radiogenic isotope data for the granitoids associated with mineralization in the Cheshmeh Khuri area in comparison with those of other prospects in the Lut Block indicate that mantle has played a crucial role in their petrogeneses and metallogeneses. Due to the crustal contamination and assimilation, the proportion of mantle component that was involved in the granitic magma shows a decrease in the Cheshmeh Khuri area. It seems that the Cheshmeh Khuri area has the lowest potential for a significant amount of Cu-Au agglomeration.

Porphyry copper deposits in the Tethyan metallogenic belt broadly occur in early Mesozoic, late Mesozoic, Paleogene, and Neogene within a wide range of tectonic setting. These deposits in Iran often occur within the Cenozoic Urumieh-Dokhtar Magmatic Arc (UDMA), mostly in the Kerman porphyry copper belt (KPCB) located in the southeast of this arc. These deposits along the UDMA are mainly associated with the granitoids of Miocene age (18.82–9.20 Ma). In this research, geochemical characteristics, Pb and Sr isotopes, tectonic environment, oxidizing conditions and source of magmas for the most important porphyry copper deposits of the UDMA have been compared and discussed. On the basis of trace element discrimination diagrams, the Kerman belt granitoids formed in a volcanic arc-type setting, whereas the Jebal Barez granitoids seem to have formed in a different tectonic setting. The Eu/Eu* of granitoids from the Kerman belt are greater than 1.2, representing the oxidizing conditions for the crystallization of the granitoid magma, whereas Jebal Barez granitoids were formed under reducing conditions. The Sr/Y ratio for Kerman granitoids is greater than 60, indicating adakitic affinities and (La/Yb)n for these granitoid rocks is between 17 and 35, suggesting that their parental magma was generated from a deep garnet-bearing source. Based on (87Sr/86Sr)i values for Kerman belt granitoids of 0.704–0.705, it is suggested that parental magmas originated from a subducted oceanic slab. In the Sarcheshmeh porphyry copper deposit, the thermal gradient of the oceanic slab at depth was less than 9 °C/Km (warm-cold slab). The oceanic slab was highly hydrated and more than 80% of the water within the oceanic slab was released in the deep zone of the sub-arc region at a depth of 110–130 Km. Under saturated conditions, the oceanic slab partially melted (20–25%). A large volume of magma and magmatic water formed Sarcheshmeh as a giant porphyry copper deposit. In the Iju deposit, a small porphyry copper deposit, the oceanic slab was slightly hydrated and minor water was released at the depth of 110–130 Km. A small volume of magma was formed due to water undersaturated melting conditions. Finally, a new hypothesis is introduced regarding the roles of down-dip thermal gradient of the oceanic slab, water content, depth of dehydration and degree of partial melting of oceanic slab which are important controls on the formation and size of the porphyry copper deposits within continental volcanic arcs.

The Torud-Chahshirin Magmatic Belt in northern Iran is defined by Tertiary porphyry, IOCG, Skarn, Manto, MVT, and Au, Ag and base metal-rich epithermal systems, and it is a part of the eastern Alborz Orogenic Belt of Iran. Mineralization in the Torud-Chahshirin Magmatic Belt occurs as veins, veinlet, and disseminated mineralization hosted by the Eocene-Oligocene volcanic, subvolcanic, and volcanoclastic rocks. Mineralization prospects of the Torud-Chahshirin Mgmatic Belt are spatially and temporally accompanied with magmatic rocks of early to middle Eocene (∼55–37 Ma.) calc-alkaline and early to late Oligocene (∼34–24 Ma.) alkaline rocks that have continually evolved through assimilation and fractional crystallization (AFC) processes at shallow crustal levels. The Robaie area is located in the Torud-Chahshirin Magmatic Belt. The dominant stratigraphic unit is composed of Eocene volcanic rocks (trachyandesitic to andesitic in composition), which are intruded by subvolcanic rocks. The subvolcanic rocks have features typical of shoshonitic affinity and are metaluminous to weakly peraluminous. These rocks are characterized by enrichment in large-ion-lithophile elements (LILEs) and light rare-earth-elements (LREEs), depletion of heavy rare-earth-elements (REEs, LaN/YbN ≈ 9.65–24.34), and high-field-strength-elements (HFSEs). Values of eNd(i) commonly show a small variation between +0.2 and +0.7, whilst 86Sr/87Sr (i) goes from 0.7056 to 0.7063. The whole set of evidence agrees with derivation of intrusive rocks of Robaie from primitive magma resulting from partial melting in a mantle wedge above a subduction zone. A sample from a dyke of biotite-hornblende diorite porphyry, with a negative eNd(i) value (−1.7), probably corresponds to a magma that underwent assimilation of crustal material. U-Pb data of zircons from dioritic stock and dyke show ages of 49.99 Ma and 50.43 Ma, respectively. Mineralization in Robaie is related to the biotite-hornblende diorite intrusions and is associated with hydrothermal alterations including argillic, argillic-silicification, argillic-sericitic, and propylitic alteration. The ore-bearing veins, veinlets, and disseminated mineralization are controlled by structures. There are two types of veins and veinlets mineralization in the Robaie area including: 1) quartz-chalcopyrite-pyrite-specularite ± gold veins, and 2) quartz-chalcopyrite-pyrite-specularite-magnetite ± gold veinlets. The highest amount of copper (>1%) and gold (>5 g/t) is associated with quartz-chalcopyrite-pyrite-specularite ± gold veins. Microthermometric study of fluid inclusions shows that homogenization temperatures are 181–422 °C and salinities of ore-forming fluids ranged from 11.1 to 17 wt% NaCl equivalent. The temperature and salinity of ore-forming fluids were lower in the formation of the quartz-chalcopyrite-pyrite-specularite ± gold veins than in the quartz-chalcopyrite-pyrite-specularite-magnetite ± gold veinlets, and fluid mixing was the most important mechanism for mineralization in the area. The mineralogy, alteration, geochemistry, fluid inclusion studies, and petrogenesis of subvolcanic rocks of the Robaie area indicate that the Robaie deposit could be classified as a member of the Iron Oxide-Copper-Gold (IOCG) deposits.

The Khur region is located in the Late Mesozoic-Cenozoic volcanic-plutonic rocks of the Lut Block, eastern Iran. There are several outcrops of subvolcanic rocks in the region which occur mainly as dike (granitoid and mafic dikes) and stock (monzonite porphyry). Volcanic rocks (basaltic andesites, andesites, trachyandesites, dacites and rhyodacites) are also abundant and cover pyroclastic rocks. U–Pb zircon ages indicate that granitic-dioritic dikes and monzonite porphyries were emplaced at 44.97 to 40.86 Ma and 41.11 Ma, respectively. Granitoid dikes are high-K calc-alkaline and metaluminous and geochemically belong to the I-type granitoids. Monzonite porphyries show I-type (and rarely A-type) signatures, with typical enrichments in alkalis, Zr and Ce, high FeOt/(FeOt+MgO) ratio and depletion in Sr and Nb. Primitive magmas of dikes, stocks and acidic volcanic rocks have formed in the lower crust and have undergone different degrees of AFC, while primitive magmas of mafic volcanic rocks have formed in the mantle and have presumably been modified by melts/fluids. Moreover, a syn to post-collision-related zone is responsible for the high magmatic rate during the Middle Eocene in the Lut Block. published

Irankuh-Emarat is an important district of Pb Zn MVT-type deposits in Iran. The deposits are hosted by Lower and Upper Cretaceous dolostone in which and several stages of mineralization were identified. The deposition of sulfide minerals occurred spatially within or close to dolostone and shale-siltstone units with replacement and open space filling textures. Field observations, mineralogical and petrographic studies show different degrees of alteration related to mineralization. Dolomite, particularly Fe-rich dolomite, ankerite, bitumen and silicified rocks are associated with the principal sulfide mineralization. Hydrothermal fluids at Irankuh had low sulfidation to form Fe-rich dolomite and ankerite within dolostone and pyrite in shale formations. Chemical analysis of representative samples within the belt show that in sphalerite, Fe content varies between 0.3 and 5.2%, Cd 150–2000 ppm. In galena, Ag varies between 150–1200 ppm and Sb 140–1200 ppm. Fluid inclusion study shows homogenization temperatures (Th) between 150–260 °C and fluid salinities 9–21% (NaCl, wt% equiv). Field observations showed that high Pb Zn ore was deposited as replacement within the dolostone member favourable for chemical reaction. In this paper, we present a conceptual model for the formation of MVT deposits in the Irankuh-Emarat district. We suggest that the hydrothermal fluid originated from the dehydration of an oceanic subduction slab, which liberated Pb, Zn, and other metals, and may have removed metals from rocks and organic material of the continental crust. The down dip thermal gradient of the oceanic slab was about 18 °C/km (hot slab). More than 90% of all the water within the oceanic slab was released in the depth zone of the forearc region (depth of 30 to 50 km). Pb isotopic compositions of Irankuh-Emarat Pb Zn deposits are 206Pb/204Pb from 18.42 to 18.45; 208Pb/204Pb from 38.53 to 38.62 and 207Pb/204Pb from 15.63 to 15.65. Very low radiogenic Pb-isotopes indicate that Pb-isotopes had an oceanic slab source and were slightly contaminated by the basement rocks. Deep-seated thrust faults formed during the early stages of subduction, (Late Cretaceous?) and played an important role in the upward migration of hydrothermal fluids from the basement to shallow depths.

The Kaviro lead deposit is located in the Lut Block, which is an important metallogenic province in Eastern Iran (lat 34°22′N, long 57°18′E). The deposit includes ore-bearing veins and veinlets emplaced in folds and hosted by middle Jurassic slate units. The ore-forming procedure can be segregated into three stages: pre-mineralization stage quartz-pyrite, main stage quartz-dolomite-pyrite-galena, and late stage calcite and pyrite. Hydrothermal alteration minerals are composed of dolomite, quartz, and calcite. Microscopic surveys show that the vein includes galena with minor amounts of pyrite as hypogene minerals. Two types of fluid inclusions are distinguished in quartz and dolomite veins. Microthermometric investigations reveal homogenization temperatures of 180–250 °C and salinities from 5 to 12.5 wt% NaCl equivalents. The ore-forming fluids of the Kaviro deposit are medium-to-low in terms of temperature and salinity. The δ34S values for the ore fluid are estimated to be between +0.94‰ and +3.27‰. The isotopic compositions of sulfur suggest that the ore-forming aqueous solutions are derived from a nonmagmatic source, probably from leaching of metamorphic rocks. The 206Pb/204Pb, 207Pb/204Pb, and 208Pb/204Pb ratios of the samples span narrow ranges from 18.514 to 18.569, 15.668 to 15.715, and 38.803 to 38.950, respectively. The 207Pb/204Pb and 208Pb/204Pb ratios plot above the evolution curves and clearly indicate a crustal source. The 207Pb/204Pb vs. 206Pb/204Pb data suggest a homogen source for Pb. Most of the galena samples in the CIM Pb-Zn deposits show high 207Pb/204Pb ratios, indicating that Pb is mainly derived from continental crust or pelagic sediment. The age of the mineralization is after the middle Jurassic. The Kaviro deposit is a metamorphic-related vein deposit, and fluid mixing is the important mechanism for its deposition.

The closure of the Paleotethys ocean in the Tethyan orogenic belt in northeastern (NE) Iran, related to the collision between Gondwana-derived terranes in the south and Laurasia in the north, remains controversial due to the sparsity of Paleozoic ophiolitic outcrops but can be constrained by contemporaneous granitoids. The Late Triassic Torbat e Jam stock in NE Iran is composed of three intrusive suites: (1) the oldest gabbro to quartz diorite intruded at 215.5 ± 0.9 Ma; (2) granodiorite to monzonite; and (3) the youngest granite to alkali granite. All three suites are metaluminous to moderately peraluminous with enrichment in LILE, low LREE/HREE fractionation with (La/Yb)N = 8.4–13.6, and small negative Eu anomalies. The Torbat e Jam stock without primary magnetite is characterized by very low magnetic susceptibility (5 × 10−5 to 6 × 10−4 SI unit), indicative of the I-type granitoids. Zircon Hf isotopic compositions show positive eHf(t) values of +2.6 to +5.7, indicative of a predominantly mantle source with minor crustal contamination. Hf model ages are consistent with the presence of Neoproterozoic juvenile sources (TDMC = 0.88 to 1.09 Ga). These geochemical data and field relationships suggest that the Torbat e Jam stock formed in a late orogenic to post-collisional tectonic setting after the closure of a secondary Paleotethys ocean (Paleotethys II), which opened as an oceanic trough during the Late Palaeozoic in the Iranian block, and closed in the Late Permian-Early Triassic Indosinian orogeny.

Paleogene igneous rocks from ∼600 km Quchan-Sabzevar-Torud magmatic belt include a thick pile of volcanic and pyroclastic rocks which intruded by younger felsic-mafic plutons. Various types of mineralization including Iron Oxide-Copper-Gold (e.g., Firouzeh mine) and porphyry Cu-Au deposits (e.g., Jalambadan mine) are associated with the Quchan-Sabzevar magmatism. In this study, we describe new zircon U-Pb ages and geochemical-isotopic data of the subvolcanic rocks from near the Firouzeh mine. The Firouzeh subvolcanic rocks consist of (quartz-bearing) monzosyenites, monzodiorites and monzonites. These rocks have typical calc-alkaline signature and are mainly metaluminous in nature. Subvolcanic rocks display enrichment in Light Rare Earth Elements (LREEs) with negative Eu anomaly. Enrichment in Large Ion Lithophile Elements (LILEs) and depletion in High-Field Strength Elements (HFSEs) are geochemical characteristics of these rocks. The Firouzeh volcanic rocks also display calc-alkaline signature and are metaluminous to peraluminous. Volcanic rocks show both enrichment in LREEs and LILEs, associated with negative Eu anomaly. Zircon U-Pb indicates ages of 43.2 ± 0.4, 42.1 ± 0.4 and 41.8 ± 0.4 Ma for monzosyenites, monzodiorites and monzonites respectively. Zircon epsilon Hf(t) shows average values of −1.49 for monzonites, +9.07 for monzodiorites and −1.06 for monzosyenites. The Hf model ages for these rocks are in the range of 850–730, 270–180 and 3150–450 Ma, respectively. Inherited zircons are abundant in monzonites and have variable Hf isotope values. The wide range of zircon eHf(t) values and abundance of inherited/xenocrystic zircons suggest a multiple source(s) for the generation of the Firouzeh subvolcanic rocks, including a mantle melt and an old crustal component. Xenocrystic zircons indicate complex crustal components. We suggest the NE Iran subvolcanic rocks including the Firouzeh igneous rocks, generated above the Sabzevar subduction zone. This subduction zone was active since Late Cretaceous time.

The Simorgh prospecting area is located in the central part of the Lut Block in eastern Iran. The Lut Block, the eastern part of the Central Iranian Microcontinent (CIM), has a complex tectonic evolution and is characterized by extensive magmatic activities with a range of geochemical signatures. The Simorgh intrusions have features typical of calc-alkaline to high-K calc-alkaline rocks, metaluminous to slightly peraluminous and formed in a volcanic arc setting. Mineralization in the area is believed to be related to these intrusions. To better understand the petrogenesis of these intrusions, we report zircon U-Pb dating and Hf isotopes and whole rock geochemistry of two granites and one diorite. Age dating using Zircon U-Pb method on pyroxene diorite porphyry stock and two granite porphyry dikes revealed 24.85 ± 0.51 Ma, 25.37 ± 0.56 Ma and 25.94 ± 0.76 Ma ages respectively (late Oligocene, Chattian). Field observations and U-Pb dating indicate that there are at least two stages of emplacement: pre-mineralization intrusions (diorite porphyry) and syn-mineralization intrusions (granite porphyry, granodiorite porphyry and pyroxene diorite porphyry). Mantle-normalized, trace-element spider diagrams display enrichment in large ion lithophile elements (LILE) and light rare earth elements ((La/Yb)N = 9.26–14.48), and depletion in high field strength elements (HFSE) and heavy rare earth elements, as well as negative Eu anomalies (Eu/Eu* = 0.49–0.91). Zircon Hf isotope data from the Simorgh intrusive rocks show largely positive eHf(t) (average = 3.6 ± 2.0). Hf model ages are ranging from 720 to 1320 Ma, indicating its derivation from a relatively juvenile source. The presence of zircon xenocrysts may prove its contamination by older continental crust (Siderian).

The Iju porphyry copper deposit is located in the Kerman copper belt in the northwest of Shahr-e-Babak city within the southern extension of the Urumieh-Dokhtar magmatic arc. Based on a cut-off grade of 0.15%, the deposit contains 24 million tonnes (Mt) of ore with an average grade of 0.4 wt% Cu. The igneous rocks at the Iju deposit are primarily made up of Upper Miocene sub-volcanic and volcanic sequences that intruded Eocene volcanic rocks. Sub-volcanic rocks comprise barren quartz-monzonite porphyry and syn-mineralized granodiorite porphyry along with andesitic volcanic rocks. Geochemical evidences show that they are co-genetic, medium- to high-potassium calc-alkaline, and likely part of a subduction zone I-type granitoid magma. These rocks are characterized by enrichment in LREEs relative to HREEs with negative Nb–Ta anomalies similar to subduction zone magmatism. All samples exhibit enriched uniform chondrite-normalized REE patterns without noticeable Eu anomalies similar to magnetite-series granitoids. The igneous rocks of the Iju deposit exhibit geochemical features similar to adakites. The U-Pb zircon dating shows 9.33 ± 0.19 Ma (Tortonian stage) for quartz-monzonite (oldest unit), 9.01 ± 0.20 Ma for granodiorite and 8.83 ± 0.19 Ma for andesite (youngest unit) unit. The initial 87Sr/86Sr and 143Nd/144Nd ratios and eNd(t) values for the quartz-monzonites are 0.704234, 0.512819 and 3.75, respectively, similar to the values for the granodiorite, which are 0.704278, 0.512813 and 3.64, respectively. In most discrimination diagrams, the Iju samples show characteristics of both oceanic slab-derived and delaminated/collisional thickened lower crust-derived adakites. The geochronological, geochemical and isotopic data for the igneous rocks of the Iju deposit indicate that after long term subduction of the Neo-Tethys oceanic crust beneath the central Iranian plate, continental collision between the Arabian and Eurasian plates during the Miocene-Pliocene led to crustal thickening, breaking-off of a subducted slab and development of an asthenospheric window, thereby facilitating partial melting of the subduction-contaminated sub-continental lithospheric mantle and thickened lower crust and generating the Cu-bearing adakites in the Iju region.

The Kuh-e-Zar deposit is located in the central part of the Khaf-Kashmar-Bardaskan Tertiary magmatic belt, NE Iran. The prevailing stratigraphic unit is composed of Cenozoic volcanic rocks (rhyolitic to andesitic in composition), which are intruded by subvolcanic plutons. Intrusive rocks spatially close to mineralization include metaluminous to peraluminous, calc-alkaline and I-type diorite, granodiorite, quartz monzonite, quartz monzodiorite, and syenogranite. The quartz monzonite and quartz monzodiorite have identical zircon U–Pb ages of ca. 40.7–41.2 Ma. The intrusions are characterized by enrichment in large-ion-lithophile elements (LILEs) and light rare-earth-elements (LREEs), depletion in heavy rare-earth-elements (REEs, LaN/YbN ≈ 7 to 9.07) and high-field-strength-elements (HFSEs) and eNd(t) ranging from − 0.06 to − 2.93 at 86Sr/87Sr(t) = 0.7054–0.7064 and 206Pb/204Pbi = 18.6–18.71. The intrusive rocks of Kuh-e-Zar are products of crustal assimilation by melts derived from the metasomatized mantle wedge above the subducting Neotethyan Ocean slab beneath SW Eurasia. Field work and mineralogical, petrological studies show that, the hydrothermal alteration produced a zone of silicification, propylitic alteration, and albitization associated with minor sericitic-argillic alteration. The mineralization of Kuh-e-Zar occurs in veins, stockworks, and breccias, which is located near or within NE − SW and NW − SE faults cutting through volcanic rocks and wall rocks. The ore minerals are dominated by specular hematite and gold with small amounts of pyrite, chalcopyrite, and galena. Hematite, goethite, malachite, covellite, and cerussite are secondary minerals. The main gangue minerals include quartz, siderite, chlorite, and albite. Microthermometric study of fluid inclusions shows homogenization temperatures at medium-high temperature of 248 to 491 °C. Salinities of ore-forming fluids are medium-low ranged from 4 to 19.2 wt% NaCl equivalent. The sulfur isotope composition of chalcopyrite (δ34S = − 2.5 to 0.9‰) suggests that sulfur was derived mainly from igneous rocks. The oxygen isotopic data (δ18Owater = 7.4–7.9‰) indicate that the ore fluids were in magmatic origin. The mineralogy, alteration, geochemistry, stable isotopes, and petrogenesis of intrusions of the Kuh-e-Zar deposit indicate it is an Eocene gold-rich iron oxide-copper-gold (IOCG) deposit.

The Maherabad, Qaleh Zari, and Hired deposits in eastern Iran are porphyry (Cu-Au)-, Iron oxide copper–gold (IOCG)-, and reduced intrusion-related gold system (RIRGS)-type mineralization, respectively. They are located within the Lut block magmatic assemblage, which is the main metallogenic province in eastern Iran. The mineral assemblages and paragenesis of the deposits indicate that highest log fO2 and log fS2 contents belong to the Qaleh Zari deposit. In contrast, the lowest values of oxygen and sulphur fugacity are related to the RIRGS system in the Hired deposit. The Maherabad mineralization has moderate log fO2 and log fS2 contents relative to the Qaleh Zari and Hired deposits. Geochemically, these three deposits are related to different types of granitoids, which occurred within the short time interval from 37 to 41 Ma. The Maherabad and Qaleh Zari intrusions are related to oxidized magnetite-series granitoids, whereas the mineralization at Hired deposit is related to the reduced ilmenite-series granitoids. Magnetite-series intrusive rocks at Hired are barren. Intrusive bodies in the three studied sites are metaluminous, high-K calc-alkaline to shoshonitic, and formed in a volcanic arc setting. However, there are distinct differences in the radiogenic isotopic composition, content of some elements and elemental ratios reflecting the effect of different sources in the formation of intrusions. The reduced granite of the Hired deposit has the lowest Eu/Eu* of

Syste'm Pour l‘Observation de la Terre (SPOT) remote sensing satellite data have useful characteristics for lineament extraction and enhancement related to the tectonic evaluation of a region. In this study, lineament features in the Bajestan area associated with the tectonic significance of the Lut Block (LB), east Iran were mapped and characterized using SPOT-5 satellite data. The structure of the Bajestan area is affected by the activity of deep strike-slip faults in the boundary of the LB. Structural elements such as faults and major joints were extracted, mapped, and analyzed by the implementation of high-Pass and standard kernels (Threshold and Sobel) filters to bands 1, 2 and 3 of SPOT-5 Level 2 A scene product of the Bajestan area. Lineament map was produced by assigning resultant filter images to red-green-blue (RGB) colour combinations of three main directions such as N-S, E-W and NE-SW. Results derived from image processing technique and statistical assessment indicate that two main orientations, including NW-SE with N-110 azimuth and NE-SW with N-40 azimuth, were dominated in the Bajestan area. The NW-SE trend has a high frequency in the study area. Based on the results of remote sensing lineament analysis and fieldwork, two dextral and sinistral strike-slip components were identified as main fault trends in the Bajestan region. Two dextral faults have acted as the cause of shear in the south and north of the Bajestan granitoid mass. Furthermore, the results indicate that the most of the lineaments in this area are extensional fractures corresponding to both the dykes emplacement and hydrothermal alteration zones. The application of SPOT-5 satellite data for structural analysis in a study region has great capability to provide very useful information of a vast area with low cost and time-consuming.

The South-West Sorkh-Kuh (SWSK) area, part of the Tertiary volcanic-plutonic rocks in the Lut Block, eastern Iran, comprises volcanic rocks intruded by intrusive rocks of hornblende diorite and biotite quartz monzonite compositions. Biotite quartz monzonite has been intensively affected by quartz-sericite-pyrite, argillic and silicification alterations and hornblende diorite shows weak propylitic and carbonate alterations. Disseminated, stockwork and vein-type styles of mineralization are associated with intrusive rocks. The vein-type mineralization with NW-SE trend is hosted by hornblende diorite. The ore in vein-type mineralization consist of quartz, chalcopyrite, pyrite, and secondary Cu-Fe minerals. Disseminated and stockwork mineralizations consist of quartz, pyrite, chalcopyrite, and secondary minerals replacing biotite quartz monzonite and hornblende diorite intrusive rocks. The highest grades in terms of Cu (3%), As (1.3%), Mo (150 ppm), Pb (362 ppm), Zn (743 ppm), and Au (278 ppb) are associated with vein-type mineralization. Intrusive rocks causing mineralization, are of metaluminous to peraluminous types with calc-alkaline to high-K calc-alkaline affinity formed in a volcanic arc setting. The enrichment of LILE (Ba, K, Cs, Sr), depletion of HFSE (Nb, P, Ti) and enrichment of LREE relative to HREE indicate the formation of source magmas above a subduction zone. The results of zircon U–Pb dating give constraints on the timing of emplacement of biotite quartz monzonite and hornblende diorite bodies at 40.16 ± 0.72 and 20.1 ± 2.1 Ma, respectively. The younger date extends the time span of mineralizations in the Lut Block from Middle Eocene to Early Oligocene (42–33 Ma.) reported by previous researchers to more recent Early Miocene times. The initial 87Sr/86Sr ratios and eNd values of both biotite quartz monzonite and hornblende diorite reside in the restricted ranges of 0.7055–0.7066 and − 0.33 to + 1.88, respectively, consistent with an origin above a subduction zone followed by crustal contaminations of the initial magma compositions, especially with regard to biotite quartz monzonite. The zircon U-Pb ages as well as geochemical and radiogenic isotope data for the intrusive bodies associated with mineralization in this study are in accordance with previous studies on intrusive bodies related to porphyry copper deposits in the Lut Block. In contrast to previous studies, this study further extends the span of mineralization events to at least Early Miocene times.

The Upper Cretaceous Nakhlak epigenetic vein-type Pb (Ag) deposit is located 55 km northeast of the town of Anarak in Isfahan Province, Iran. The deposit contains 7 Mt of galena-barite ore with an average grade of 8.33% Pb, 0.38% Zn, and 72 ppm Ag. The ore mineralization occurs as stratabound, epigenetic, steeply dipping, east-west–trending veins in faulted- or fracture-controlled Upper Cretaceous Sadar carbonates. Galena and barite are the primary minerals. Minor sphalerite, tennantite-tetrahedrite, pyrite, and chalcopyrite occur as inclusions in galena. Cerussite with minor amounts of anglesite and plattnerite formed in the oxidized supergene zone. The ore and ore-related minerals were deposited in the hydrothermally dolomitized carbonate host rock containing saddle-shaped dolomite. Geochemically, the dolomitized carbonate host rocks are enriched in MgO, Fe 2 O 3 , MnO, Pb, Zn, and Ba, but depleted in CaO. The galena concentrate contains high values of Ag (932 ppm), Sb (342 ppm), Cu (422 ppm), As (91 ppm), and Zn (296 ppm); the presence of these trace elements indicates a low-temperature type of galena mineralization. This interpretation is corroborated by fluid inclusions containing 12.98 wt.% NaCl equivalent salinity; the inclusions homogenize at the low temperature of about 152.1 °C. The similarity between δ 34 S (V-CDT) values in Nakhlak barite and Permian–Triassic δ 34 S marine sulfate values indicates that the Nakhlak sulfur was probably provided from evaporates of Permian–Triassic age. The δ 34 S (V-CDT) values of galena and barite samples occupy the ranges of − 1.04‰ to + 8.62‰ and + 10.95‰ to + 13.71‰, respectively, and are similar to Mississippi Valley–type (MVT) deposits. The low-temperature basinal fluids, evaporate-originated sulfur, and fault- or fracture-controlled galena-rich veins in the Nakhlak deposit resemble the type of geological features documented in Pb-rich MVT deposits.

The Hamech area is located in the west of Kuh-e-Shah volcano-plutonic complex, close to the boundary between the Lut Block and Sistan Suture Zone (SSZ), and is composed of monzonite to diorite porphyries and rare gabbro that intruded into older volcanic rocks. U-Pb zircon dating indicates an age of 36.9 ± 1 Ma for gabbro (Late Eocene, Priabonian) and 38.6 ± 0.5 Ma for dacite (Late Eocene, Bartonian). Geochemically, the studied intrusions are dominantly I-type, high-K calc-alkaline, and metaluminous features. Primitive mantle-normalized trace-element spider diagrams of these rocks present enrichment in ion lithophile elements such as Cs, Rb, Ba, K, and Sr and depletion in high field strength elements such as Nb, Ti, Zr, and heavy rare earth elements. Besides, chondrite-normalized rare earth elements plots of the rocks show enrichment in light rare earth elements (6.85 < LaN/YbN < 9.72) and a lack or weak negative Eu anomaly (Eu/Eu* = 0.81–1.02). The initial 87Sr/86Sr and 143Nd/144Nd ratios for the rocks from 0.704541 to 0.704880 and from 0.512633 to 0.512691, respectively, when recalculated to an age of 39 Ma. The εNd(i) values vary from +0.87 to +1.99, which fits into a suprasubduction mantle wedge source for the parental melts. All data suggest that the Hamech intrusions developed in a low maturity continental margin arc setting related to the convergence of the Afghan and Lut Blocks and subduction of Sistan oceanic crust during the Eocene. published

The Kuh-e-Shah complex includes the Paleogene volcano-plutonic belt of the Lut Block, eastern Iran. The volcanic rocks which outcropped in this complex mainly consist of trachy-andesites, andesites, and basaltic-andesites that mineralogically contain plagioclase, pyroxene, hornblende, and minor biotite and olivine. Geochemically, they have features typical of high-K calc-alkaline to shoshsonitic magmas with enrichment in large ion lithophile elements (LILE), and depletion in high field strength elements (HFSE) and heavy rare earth elements (HREE). Chondrite-normalized REE plots show enrichment in light REE (4.9 < LaN/YbN < 11.6), Nb depletion and the slight negative Eu anomalies (Eu/Eu* = 0.80–0.99). Tectonic discrimination diagrams are used to infer a volcanic arc setting related to a continental subduction zone. It is concluded that the studied volcanic rocks have resulted from FC of a parental magma which formed by partial melting of the subducted oceanic crust and the overlying mantle wedge with spinel-lherzolite composition. Zircon Usingle bondPb dating indicates an age of 38.6 to 38.9 Ma for volcanic rocks (Middle Eocene, Bartonian). Initial 87Sr/86Sr and 143Nd/144Nd ratios (0.704350–0.704820 and 0.512619–0.512779, resp.), are compatible with parental melts formation in a subduction mantle wedge. The ɛNdi values (+0.60 to +3.73) are in the range of mantle-derived melts. We suggest that volcanic rocks of the Lut Block are part of the Paleogene volcanism resulted from the Sistan oceanic crust subduction under the Lut Block during the Cretaceous. published

The Gazu Cu deposit is located at the boundary between the Lut and Tabas Blocks in Central Iranian Microcontinent. The intrusions in the Gazu area are characterized by SiO2 contents ranging from 52.6 to 66.4 wt.%, K2O from 1.98 to 3.64 wt.%, and Na2O from 2.5 to 5.2 wt.%. The intrusions have features typical of high-K calc-alkaline rocks, are metaluminous to weakly peraluminous, and formed in a volcanic arc setting. Zircon U–Pb age data for hornblende monzonite porphyry, hornblende monzodiorite porphyry, pyroxene monzonite, hornblende granite, hornblende quartz monzonite porphyry, and hornblende diorite porphyry are 68.1 ± 1.7 Ma, 67.74 ± 0.72 Ma, 67.41 ± 0.94 Ma, 65.9 ± 3.7 Ma, 65.1 ± 1.2 Ma, and 60.2 ± 1.2 Ma, respectively. Copper mineralization is related to the hornblende granite and hornblende quartz monzonite porphyry. Field observations and the U–Pb dating indicated three stages for intrusive rock emplacement: pre-mineralization intrusions (hornblende monzonite porphyry, hornblende monzodiorite porphyry, and pyroxene monzonite), syn-mineralization intrusions (hornblende granite and hornblende quartz monzonite porphyry), and post-mineralization intrusions (hornblende diorite porphyry). Mantle-normalized, trace-element spider diagrams display enrichment in large ion lithophile elements, such as Rb, Ba, K, and Cs, and depletion in high field strength elements, e.g., Nb, Ti, Zr, Y, and heavy rare earth elements, with light rare earth element enrichment ((La/Yb)N = 6.4–13.4) and a weak negative Eu anomaly (Eu/Eu* = 0.87–1.01). Zircon Hf isotope data indicate that the Gazu intrusive rocks are characterized by low positive eHf(t) values, with an average of 4.23, and show young Hf model ages (789–188 Ma), indicating derivation from juvenile crust. Relatively low positive eHf(t) values, the wide range for eHf(t), and the presence of zircon xenocrysts can be explained by involvement of a mantle component that mixed with older continental crust (Cadomian).

The Irankuh-Emarat Pb-Zn belt is situated within the forearc Urumieh-Dokhtar zone of western part of Iran and it is classified as Mississippi Valley TYPE Pb-Zn mineralization. According to Karimpour and Sadeghi (2018) deep-seated thrust faults played an important role in the upward migration of hydrothermal fluids from the basement to shallow depths. The style and shape of mineralization are controlled by the host rocks. Rajabi et al. (2019) commented on the model presented by Karimpour and Sadeghi (2018) but the proposed syngenetic MVT model presented by Rajabi et al. (2019) is not acceptable based on the age of the mineralization at Irankuh-Ahangharan belt and also the role of deep-seated thrust faults in the mineralization area and its spatial distribution and association with the main ore bodies was completely omitted. In addition, the work presented by Karimpour and Sadeghi (2018) did not explain metallogenic aspect of all Zn-Pb deposits in the area and other belts and the proposed model is applicable to Pb-Zn deposits in the Irankuh-Emarat belt and not necessary to explain other Pb-Zn mineralization elsewhere in Iran.

The Shah Soltan Ali area (SSA) is located in the eastern part of the Lut Block metallogenic province. In this area different types of sub-volcanic intrusions including diorite porphyry, monzonite porphyry and monzodiorite porphyry have intruded into basaltic and andesitic rocks. Zircon U–Pb dating and field observations indicate that intermediate to mafic volcanic rocks (38.9 Ma) are older than subvolcanic units (38.3 Ma). The subvolcanic intrusions show high-K calc-alkaline to shoshonitic affinity and are metaluminous. Based on mineralogy, high values of magnetic susceptibility [(634 to 3208) × 10−5 SI], and low initial 87Sr/86Sr ratios, they are classified as belonging to the magnetite-series of oxidant I-type granitoids and are characterized by an enrichment in LREEs relative to HREEs, with negative Nb, Ti, Zr and Eu anomalies. These granitoids are related to volcanic arc (VAG) and were generated in an active continental margin. Low initial 87Sr/86Sr ratios (0.7043 to 0.7052) and positive eNd values (+1.48 to +3.82) indicate that the parental magma was derived from mantle wedge. Parental magma was probably formed by low degree of partial melting and metasomatized by slab derived fluids. Then assimilation and fractional crystallization processes (AFC) produced the SSA rocks. This magma during the ascent was contaminated with the crustal material. All data suggest that Middle-Late Eocene epoch magmatism in the SSA area, occurred during subduction of Neo-Tethys Ocean in east of Iran (between Afghan and Lut Blocks).

© 2018, © 2018 Informa UK Limited, trading as Taylor & Francis Group. The integration of information extracted from the Syste`m Pour l’Observation de la Terre (SPOT) and the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) data, comprehensive field and mineralogy studies demonstrates that phyllic alteration zone associated with northwestern (NW)–southeastern (SE) structural fractures is a high potential zone for Cu–Fe–Au vein-type mineralisation in the Bajestan region, the Lut block, east Iran. The fractal pattern was calculated for fractures map using the Box-Counting algorithm to the SPOT-5 data. Statistical parameters of fractures, such as density, intensity and fractures’ intersection were also determined. Band composition, specialised band ratio and Spectral Angle Mapper (SAM) classification methods were implemented to the ASTER dataset for detecting hydrothermal alteration zones, such as propylitic, phyllic, argillic and gossan. Results indicate that the maximum value of the fractal dimension, intensity, density and the intersection of the fractures are concentrated in the NW and SE parts of SPOT image maps. In the other hand, phyllic alteration zone containing sericite, alunite, kaolinite and jarosite mineral assemblages was also identified in several zones of the NW and SE parts of the ASTER image maps. Integration of the results indicates the high potential zones for the occurrence of Cu–Fe–Au mineralisation in the Bajestan region.

The Mahoor Cu–Zn-bearing porphyritic granitoid rocks belong to the Lut Block volcanic–plutonic belt (central Eastern Iran). These granitoid rocks occur mainly as dykes and stocks that intrude into Eocene volcanics and pyroclastic rocks. Petrographically, all the studied intrusives display porphyritic textures with mm-sized phenocrysts, most commonly of plagioclase and hornblende, embedded in a fine-grained groundmass with variable amounts of plagioclase, hornblende, clinopyroxene, quartz and opaque minerals. Hydrothermal alteration affected these granitoid rocks, as revealed by the common occurrence of sericite, chlorite, titanite, epidote and calcite. Chemical classification criteria show that the intrusives may be named as gabbrodiorites, diorites, monzodiorites and tonalites. Major elements geochemistry reveals that all the studied lithologies are typically metaluminous (A/CNK ⩽ 0.9). Magnetic susceptibility (1485 × 10 −5 SI) together with mineralogical and geochemical features shows that they belong to magnetite granitoid series (I-type). Trace element patterns normalized to chondrite and primitive mantle are very similar to each other and show enrichments in LREE relative to HREE and in LILE relative to HFSE, as well as negative anomalies of Ta, Nb and Ti. Eu/Eu ∗ ratios vary from 0.88 (in the most mafic composition) to 0.65, showing that plagioclase played a role in magma differentiation. LA-MC-ICP-MS U–Pb zircon data from a diorite, yielded similar concordia ages of ca. 31.88 ± 0.2 Ma (Error: 2 σ ), which corresponds to the Oligocene period. These granitoid rocks have ( 87 Sr/ 86 Sr) i values vary between 0.7055 and 0.7063. In terms of isotopic compositions, while eNdi is between −0.6 and −2.5, suggesting that magmas underwent contamination through being exposed to the continental crust. The whole set of geochemical data agree with the emplacement of the studied intrusions in a magmatic belt above a subduction zone. Primitive magmas should have formed by melting of mantle wedge peridotite, and during magma ascent to crustal levels, both magma differentiations took place by crystal fractionation and crustal contamination. Sulfide mineralizations (pyrite, chalcopyrite and sphalerite) related to these granitoid rocks is common and occurs as both disseminated and hydrothermal veins, indicating a high mineralization potential for this area.

The Sechangi lead–zinc (–copper) deposit lies in the Lut block metallogenic province of Eastern Iran. This deposit consists of ore-bearing vein emplaced along fault zone and hosted by Late Eocene monzonite porphyry. Hydrothermal alteration minerals developed in the wall rock include quartz, kaolinite, illite, and calcite. Microscopic studies reveal that the vein contains galena and sphalerite with minor chalcopyrite and pyrite as hypogene minerals and cerussite, anglesite, covellite, malachite, hematite, and goethite as secondary minerals. Fluorite and quartz are the dominant gangue minerals and show a close relationship with sulfide mineralization. Calculated δ 34 S values for the ore fluid vary between −9.9‰ and −5.9‰. Sulfur isotopic compositions suggest that the ore-forming aqueous solutions were derived from magmatic source and mixed with isotopically light sulfur, probably leached from the volcanic and plutonic country rocks. Microthermometric study of fluid inclusions indicates homogenization temperatures of 151–352 °C. Salinities of ore-forming fluids ranged from 0.2 to 16.5 wt.% NaCl equivalent. The ore-forming fluids of the Sechangi deposit are medium- to low-temperature and salinity. Fluid mixing may have played an important role during Pb–Zn (–Cu) mineralization. The key factors allowing for metal transport and precipitation during ore formation include the sourcing of magmatic fluids with high contents of metallogenic elements and the mixing of these hydrothermal fluids with meteoric waters resulting in the formation of deposit. In terms of the genetic type of deposit, the Sechangi is classified as a volcanic–subvolcanic hydrothermal-related vein deposit.

There are several intermediate (SiO2 = 57.4–61.2 wt.%) subvolcanic bodies in the Bisheh area of eastern Iran. Petrochemical studies show that these bodies are calc-alkaline and metaluminous (A/NK ≥ 1.68, A/CNK ≤ 0.99) diorite porphyries. They are enriched in large-ion lithophile elements (LILE) and have negative anomalies of Nb, Ti, Ta, and P. Chondrite-normalized REE patterns exhibit light-rare-earth-elements (LREE) enrichment, with mildly fractionated REE patterns ((La/Yb)N

The world-class Sangan iron skarn deposit with a proven reserve of > 1000 Mt iron ore @ 53% Fe, is located in the Khaf-Kashmar-Bardaskan Volcano-Plutonic Metallogenic Belt (KKB-VPMB) of northeastern Iran along the E–W trending regional Doruneh Fault, north of the Lut Block. Skarn mineralization occurs at the contact of the 39.1 ± 0.6 Ma to 38.3 ± 0.5 Ma Middle Eocene syenite to syenogranite porphyry source pluton with Cretaceous carbonate rocks. The source pluton is part of an I-type, calcalkaline granitoid series with potassium to shoshonitic affinity, metaluminous to slightly peraluminous character. The granitoids are enriched in LILE (Cs, Rb, Ba, K, Th, and U) and LREE (La and Ce), are depleted in HFSE (Nb, Y, Ta, and Ti), HREE (Yb and Lu) and Eu, which together with the low Sr (96 to 362 ppm) and (La/Yb) N contents suggest a metasomatized, slab-derived mantel source within the Cenozoic volcanoplutonic continental arc of northeaster Iran. The location of the skarn orebodies is controlled by the regional E–W Doruneh Fault structure, and the spatial distribution and the two, calcic and magnesian, skarns is controlled by the composition of the carbonate protolith that consists of limestone in the west and dolomite in the east. The chemistry of the skarn minerals reflects the composition of the protoliths. The western skarn is dominated by ca-rich calcsilicates that consist of prograde Ca-rich garnet (Adr 50–97 Grs 0–45 Sps-Alm 2 -7 ), Ca–Fe-rich pyroxene (Hd 75.6 Di 20 Jo 4.5 ), K–Cl–F-bearing Fe–Ca-rich amphibole ferrohastingsite (Fe 4.4 Ca 2 Mg 0.5 K 0.4 Na 0.3 )(Si 6.5 Al 1.8 O 22 )(Cl, F, OH) 2 in endoskarns, and retrograde ferroactinolite (Fe 4.2 Ca 2 MgMn 0.04 Na 0.1 K 0.06 )(Si 7.8 Al 0.2 O 22 )(F, Cl, OH) 2 and Fe-rich chlorite ripidolite (Fe 4.3 Mg 1.1 Ca 0.06 Mn 0.01 )(Al 2.8 Si 3 O 10 )(OH) 8 in the exoskarns. Wollasonite, plagioclase, and K-feldspar have been additionally formed together with ferrohastingsite in the endoskarns. The eastern magnesian skarn is typically phlogopite-rich (K 0.9 Mg 2.7 Fe 0.2 Na 0.02 )(Si 2.9 Al 1.2 O 10 ) (OH, F) 2 , and consists of prograde forsterite (Fo 97.0 Fa 2.7 ), diopsidic pyroxene (Hd 0.2 Di 0.88 ), and retrograde Mg-rich actinolite, Mg-rich chlorite clinochlore (Mg 4.5 Fe 0.1 K 0.05 )(Al 1.8 Si 2.7 O 10 )(OH) 8 , serpentine and talc. Iron mineralization overprints the calcsilicate skarns in both the western and the eastern skarns and is magnesian in the eastern orebodies (3.65 wt.% MgO). The iron ore consists of a number of high grade, replacement, and magnetite orebodies with minor amounts of pyrrhotite, chalcopyrite, and pyrite indicating a large scale metasomatic transfer of iron bearing fluids during Middle Eocene magmatic activity at the KKB-VPMB.

The Khopik porphyry copper (Au, Mo) prospect in Eastern Iran is associated with a succession of Middle to Late Eocene I-type, high-K, calc-alkaline to shoshonite, monzonitic to dioritic subvolcanic porphyry stocks emplaced within cogenetic volcanic rocks. Laser-ablation U-Pb zircon ages indicate that the monzonite stocks crystallized over a short time span during the Middle Eocene (39.0 ± 0.8 Ma to 38.2 ± 0.8 Ma) as result of subduction of the Afghan block beneath the Lut block. Porphyry copper mineralization is hosted by the monzonitic intrusions and is associated with a hydrothermal alteration that includes potassic, sericitic-potassic, quartz-sericite-carbonate-pyrite (QSCP), quartz-carbonate-pyrite (QCP), and propylitic zones. Mineralization occurs as disseminated to stockwork styles, and as minor hydrothermal breccias. Some mineralization occurs in fault zones as quartz-sulfide veins telescoped onto the porphyry system. The main ore minerals are chalcopyrite and bornite with minorpyrite and magnetite and the highest Cu (0.01–0.9 wt. %), Au (> 2 ppm), and Mo ( Unidirectional, pre-ore stage solidification texture (UST) represented by comb-quartz layers within the potassic alteration zone formed from a hypersaline brine (57–73 wt. % NaCl equiv.), low density vapor-rich fluids (4–22 wt. % NaCl equiv.) at temperatures of 482 °C to over 600 °C. The isotopic composition of oxygen (δ18Owater = 8.7–8.9 ‰) suggests that the quartz layers crystallized from magmatic-hydrothermal fluids that exsolved in the upper part of the monzonitic intrusions. Potassic alteration formed from high salinity fluids (51–73 wt. %) at temperatures between 432–592 °C, and low salinity vapor-rich solutions with 11–19 wt. % NaCl equiv. Later veinlets in the QSCP zone formed from lower salinity fluids ( The widespread presence of Middle Eocene to Lower Oligocene magmatism and mineralization in Eastern Iran suggests the presence of another important porphyry copper belt in addition to the northwest-southeast Urumieh-Dokhtar copper belt of Iran.

Using fuzzy analytical hierarchy process (AHP) technique, we propose a method for mineral prospectivity mapping (MPM) which is commonly used for exploration of mineral deposits. The fuzzy AHP is a popular technique which has been applied for multi-criteria decision-making (MCDM) problems. In this paper we used fuzzy AHP and geospatial information system (GIS) to generate prospectivity model for Iron Oxide Copper-Gold (IOCG) mineralization on the basis of its conceptual model and geo-evidence layers derived from geological, geochemical, and geophysical data in Taherabad area, eastern Iran. The FuzzyAHP was used to determine the weights belonging to each criterion. Three geoscientists knowledge on exploration of IOCG-type mineralization have been applied to assign weights to evidence layers in fuzzy AHP MPM approach. After assigning normalized weights to all evidential layers, fuzzy operator was applied to integrate weighted evidence layers. Finally for evaluating the ability of the applied approach to delineate reliable target areas, locations of known mineral deposits in the study area were used. The results demonstrate the acceptable outcomes for IOCG exploration.

The Golgohar iron mine is located southwest of Sirjan in the Sanandaj-Sirjan structural zone. The Golgohar ore deposit occurs mainly in the forms of massive, dispersed in altered rocks and rarely stratabound mineralizations, which is related to a fault zone. The mineralization is hosted by metapelites and metabasites. To clarify the paleotectonic, P-T condition of metamorphism and the genesis of the Golgohar ore deposit we report ICP-MS data of metamorphic rocks and EPMA data of feldspar, biotite, amphibole, and magnetite of host rocks and the mineralization. The protolith of metapelites are classified as shale and Fe-bearing shale. The chondrite-normalized REE patterns show enrichment in LREE, fairly flat HREE and negative Eu anomaly. The REE and other geochemical features of the shales support an undifferentiated arc precipitation environment. Based on the relative age of the protoliths, the shales formed during the Late Precambrian-Early Cambrian Pan-African orogeny. The protoliths of amphibolites were calc-alkaline basalt to andesite, which formed in a continental island arc setting. Geochemical data of the amphibolites suggest that the magma was derived from a depleted mantle that was contaminated by melts of subducted sediments. The igneous rocks were also formed during the Pan African orogeny. At the orogenic episode, the deep faulting generated a hydrothermal conduit to form the mineralization in this area. The compositional variations of the magnetite in the mineralization zones and the altered rocks were controlled by the compositions of fluid and the host rocks, the fugacity of oxygen and sulfur, the temperature, and the solubility of elements in the fluid. Large volume of the mineralization crosscutting the host rock is clearly controlled by structure. The presence of dispersed alteration zones, geochemical features such as high values of transitional elements (Co, V) in the magnetite mineral, the presence of xenoliths with high V and Ti contents in the mineralization zones and the stable isotope data indicate that the Golgohar ore deposit formed from high-density magmatic fluids in a subduction zone. The amphibolite host rock contains repidolite, magnesio-hornblende, pargasite, tschermakite, actinolite, phlogopite, andesine-oligoclase-albite, K-feldspar, and quartz. The sedimentary, igneous, and mineralized rocks had undergone metamorphism in the upper greenschist and amphibolite facies (450–700 °C and 6–10 kbar) at the Middle Jurassic, during the Middle Cimmerian tectonic phase. After these events, the deposit has been exposed, oxidized, weathered, and then buried by the Quaternary sediments. Thus, sedimentation and magmatism events occurred during Proto-Tethys subduction in the Cadomian arc, which is related to the Pan-African orogeny. Subsequently, in the late stage of subduction, magmatic fluids were responsible for the multiphase mineralization in the Golgohar area, while at the lateral stage of mineralization, they were accompanied by the mixing of sulfur-rich fluids (evaporative sulfate).

The Kooh-Shah region located in a Tertiary volcanic–plutonic belt of the Lut Block in eastern Iran comprises several subvolcanic intermediate to acidic intrusive rocks, diorite to syenite in composition, which have intruded into volcanic rocks. The Kooh-Shah granitoid rocks are characterized by enrichment in large ion-lithophile elements (LILE: e.g. Sr, Ba, Rb) and depletion in high field-strength elements (HFSE: e.g. Nb, Ta, Ti). The chondrite-normalized REE patterns are characterized by moderate LREE enrichment (La/Yb)N=6.01–10.01, medium-heavy REE enrichment, and absence of Eu anomalies. The Kooh-Shah intrusive rocks are metaluminous, shoshonitic with calc-alkaline affinity and high values of magnetic susceptibility, and classified as the magnetite-series of oxidant I-type granitoids. The age of Kooh-Shah granitoid rocks based on zircon U–Pb age dating is 39.7±0.7 Ma (=Middle Eocene) and the ranges of their initial 87Sr/86Sr and 143Nd/144Nd ratios are from 0.704812 to 0.704920 and 0.512579 to 0.512644, respectively, when recalculated to an age of 39 Ma. The initial cNd isotope values for the Kooh-Shah intrusive rocks range from −0.18 to 1.09. This geochemical data indicates that the Kooh-Shah granitoid rocks formed from depleted mantle in an island arc setting. The geochemical signature of the studied granitoid rocks represents a characteristic guide for future exploration of copper-gold porphyry-type deposits in the Lut block.

Eastern Iran has great potential for the discovery of different types of mineralization. The study area encompasses Tertiary magmatism in the northern Lut block located in northern Khur, South Khorasan, eastern Iran and is mostly covered by volcanic rocks, which are intruded by porphyritic subvolcanic intrusions in some places. Application of the spectral angle mapper (SAM) technique to Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) images detected sericitic, argillic, and propylitic alterations, silicification, and secondary iron oxides. The alteration is linear and associated within vein-type mineralization. Twelve prospective areas are selected for detailed exploration and based on our processing results, in addition to NW–SE faults, which are associated with Cu mineralization indications, NE–SW faults are also shown to be important. Based on the presence of subvolcanic rocks and numerous Cu ± Fb-Zn vein-type mineralizations, extensive alteration, high anomaly of Cu and Zn (up to 100 ppm), the age (43.6 to 31.4 Ma) and the initial 87Sr/86Sr ratio (0.7047 to 0.7065) of the igneous rocks, and the metallogenic epoch of the Lut block (middle Eocene–lower Oligocene) for the formation of porphyry Cu and epithermal deposits, the studied area shows great potential for porphyry copper deposits.

The area of Arghash in northeast Iran, prominent for its gold mineralization, was newly mapped on a scale of 1:20,000 with particular attention to the occurring generations of igneous rocks. In addition, geochronological and geochemical investigations were carried out. The oldest geological unit is a late Precambrian, hornblende-bearing diorite pluton with low-K composition and primitive isotope signatures. This diorite (U–Pb zircon age 554 ± 6 Ma) is most likely a remnant from a Peri-Gondwana island-arc or back-arc basin. About one-third of the map area is interpreted as an Upper Cretaceous magmatic arc consisting of a volcanic and a plutonic part. The plutonic part is represented by a suite of hornblende-bearing medium-K, I-type granitoids (minor diorite, mainly quartz–monzodiorite and granodiorite) dated at 92.8 ± 1.3 Ma (U–Pb zircon age). The volcanic part comprises medium-K andesite, dacite and tuffitic rocks and must be at least slightly older, because it is locally affected by contact metamorphism through the hornblende–granitoids. The Upper Cretaceous arc magmatism in the Arghash Massif is probably related to the northward subduction of the Sabzevar oceanic basin, which holds a back-arc position behind the main Neotethys subduction front. Small occurrences of pillow basalts and sediments (sandstone, conglomerate, limestone) tectonically intercalated in the older volcanic series may be relics of earlier Cretaceous or even pre-Cretaceous rocks. In the early Cenozoic, the Cretaceous magmatic arc was intruded by bodies of felsic, weakly peraluminous granite (U–Pb zircon age 55.4 ± 2.3 Ma). Another strong pulse of magmatism followed slightly later in the Eocene, producing large masses of andesitic to dacitic volcanic rocks. The geochemistry of this prominent Eocene volcanism is very distinct, with a high-K signature and trace element contents similar to shoshonitic series (high P, Zr, Cr, Sr and Ba). High Sr/Y ratios feature affinities to adakite magmas. The Eocene magmatism in the Arghash Massif is interpreted as related to thermal anomalies in crust and mantle that developed when the Sabzevar subduction system collapsed. The youngest magmatic activities in the Arghash Massif are lamprophyres and small intrusions of quartz–monzodiorite porphyries, which cut through all other rocks including an Oligocene–Miocene conglomerate cover series.

Porphyritic granitoids that host the Sangan iron mine deposit belong to the Khaf–Kashmar–Bardaskan volcanoplutonic belt in northeastern Iran. These intrusive rocks, mostly quartz monzonite to syenogranite porphyries, have been divided into three groups on the basis of crosscutting relationships and zircon U–Pb dating: (1) group 1, 42.3 ± 0.8 Ma, (2) group 2, 40.0 ± 0.5 Ma, and (3) group 3, 39.2 ± 0.6 Ma. The group 1 and 2 rocks host magnetite mineralization, whereas the group 3 intrusions are interpreted as syn-mineralization. They have features typical of high-K alkali-calcic to calc-alkalic magnesian rocks and are metaluminous to weakly peraluminous formed in a volcanic arc setting. Mantle-normalized, trace-element spider diagrams display enrichment in large ion lithophile elements, such as Rb, Ba, K, and Cs, and depletion in high field strength elements, e.g., Nb, Ti, Ta, Zr, Y, and heavy rare earth elements, with moderate to strong light rare earth elements enrichment ((La/Yb) N = 24.8–7.6) and a negative Eu anomaly. The parental magmas are probably derived from partial melting of mantle that had been metasomatized by a slab-derived fluid. During the upward migration of these melts, additional input of crustal materials could account for the high K characteristic for most of the intrusive rocks around the Sangan mine area. Textural evidence and mineral assemblages indicate the Sangan Fe-skarn is an oxidized magmatic-hydrothermal system caused by the group 3 intrusions.

The Paleo-Tethys ocean opened in Silurian time, and its subduction under the Turan plate started in the Late Devonian. By Late Triassic time (225 Ma), no Paleo-Tethys crust remained on the surface of the Iranian plate. Subsequently, however, obduction of the Turan plate over the Iranian plate emplaced allochthonous sheets in what is now northeastern Iran. The sheets contain meta-ophiolites, which have been dated at 281.4 and 277.4 Ma by the 40 Ar– 39 Ar method. These remnant Paleo-Tethys meta-ophiolites and associated metaflysch sequences were intruded by the Dehnow diorite and Kuhsangi granodiorite. Zircon U–Pb dating indicates that the age of the Kuhsangi granodiorite is 217 ± 4 Ma and that of the Dehnow diorite is 215 ± 4 Ma (Late Triassic, Norian). The granodiorite and diorite have magnetic susceptibilities of between 5 � 10 � 5

Ab stract: Problem statement: The Muteh mining district is located in 70 km northeast of Golpaygan city within the Sanandaj-Sirjan metamorphic belt. There are 2 gold mines, 7 gold occurrences and nu merous mineral indices in the Muteh gold district. There are few researches on Muteh gold district, but a detailed model is not clear yet. The aim of this study is to determine mineralogy of gold-bearing rocks and the role of these rocks in concentration of gold and to improve our knowledge about Muteh model. Approach: Detailed fieldwork carried out at different scales at the Muteh district. About 50 outcrops samples examined petrographically. Fifteen samples containing veinlets of sulfides and quartz selected for H, O and S stable isotope analysis. Petrography characterized by optical microscopy, Scanning Electron Microscopy (SEM) and X-Ray powder Diffraction (XRD) analysis. Results: Geological studies indicated that the study area show a major poly-phase metamorphism. Since the latest metamorphism was weaker than the earlier ones, the older rocks were affected by more intense metamorphism. The metamorphic rocks mainly consist of schists, quartzite, marble, amphibolite and gneisses. These rocks show two foliations (S1 and S2). The S2 foliation is the major phase in the metamorphic rocks. Pyrite is the most abundant and the important gold-bearing mineral at the study area. Based on evidences of deformation (S2) and crystallization, three main types of pyrites can be distinguished in the Muteh deposit: (1) pre-tectonic or gold bearing pyrite (2) syn-tectonic or disseminated pyrites along the foliation of the host rocks. (3) pyrite aggregates in the host rocks or in the metamorphic segregation quartz veins crosscutting the foliation of the host rocks. The sulfur isotope studies were carried out on pyrites within quartz veinlets, biotite schist and meta-volcanic rocks at the Muteh deposit. Five available data are highly variable even from the same types of hosted rocks and their � 34 S are +2.2, 6.6, 9.1, 13.9 and 16.9‰. Conclusion: There are three generations of pyrite in Muteh gold district. According to isotope data, it seems that source of sulfurs were not homogenous. The values showed more than one geological event for generation of pyrites in the study area. Compositions of sulfur isotopes indicated several different sources or processes for the sulfide fluids. The sulfur of these pyrites might have derived either directly from regional metamorphism that produced the metamorphic fluid or through dissolution and leaching of pre-existing sulfide-bearing minerals.